properties Methods of a class can manipulate that class’s private data members Methods of a class can manipulate that class’s private data members Classes provide public properties to allow clients to set ( assign value to) or get(obtain value of) private data members Classes provide public properties to allow clients to set ( assign value to) or get(obtain value of) private data members __property void set_Hour( int val) __property void set_Hour( int val) { hour = (val >=0 &&val =0 &&val<24)?val:0); } __property int get_Hour() __property int get_Hour() { return hour; return hour; }

properties Providing set and get capabilities appears to be the same as making the variables public Providing set and get capabilities appears to be the same as making the variables public Every property method name must be preceded by either set_ or get_ Every property method name must be preceded by either set_ or get_ __property void set_propertyName() __property void set_propertyName() PropertyName specifies the name of property. PropertyName specifies the name of property. Hour is scalar property Hour is scalar property Scalar property is property that can be accessed like variables. We assign value to scalar properties using = operator. When assignment occurs, the code in the set accessor for that property executes Scalar property is property that can be accessed like variables. We assign value to scalar properties using = operator. When assignment occurs, the code in the set accessor for that property executes Time *time = new Time(); Time *time = new Time(); time->Hour = Int32::Parse(Console::ReadLine()); time->Hour = Int32::Parse(Console::ReadLine());

Static members Static variable: all class objects share only one copy of a static variable. Static variable: all class objects share only one copy of a static variable. Static variable represents class-wide information Static variable represents class-wide information Declaration Declaration static in count; static in count; Static member can be initialized in its declaration Static member can be initialized in its declaration Public static data can be accessed from client code through the class name using the scope resolution operator:: Public static data can be accessed from client code through the class name using the scope resolution operator:: The private static data can be accessed only through methods or property of the class The private static data can be accessed only through methods or property of the class

Static methods To enable a client to access a private static member when no objects of the class exists, the class must provide a public static method or property To enable a client to access a private static member when no objects of the class exists, the class must provide a public static method or property A static method cannot access non- static data A static method cannot access non- static data Static variable and static methods exist even when there are no objects of that class in which the static members are defined Static variable and static methods exist even when there are no objects of that class in which the static members are defined

Inheritance The previously defined class is called the base class The previously defined class is called the base class New class is referred to as the derived class New class is referred to as the derived class (other language, Java refer to base as superclass and derived class as subclass) (other language, Java refer to base as superclass and derived class as subclass)

Point class public __gc class Point public __gc class Point { public: public: Point(); Point(); Point(int, int); Point(int, int); __property int get_X(){return x;} __property int get_X(){return x;} __property void set_X(int val){x = val;} __property void set_X(int val){x = val;} __property int get_Y(){ return y;} __property int get_Y(){ return y;} __property void set_Y(int val){ y = val;} __property void set_Y(int val){ y = val;} String *ToString(); String *ToString(); private: private: int x,y; int x,y; }; };

String * Point::ToString() String * Point::ToString() { return String::Concat(S”[“,x.ToString(), S”,”,y.ToString(), S”]”); return String::Concat(S”[“,x.ToString(), S”,”,y.ToString(), S”]”); } Point::Point(){ } Point::Point(){ } Point::Point( int xval, int yval) Point::Point( int xval, int yval) { x = xval; x = xval; y = yval; y = yval; }

Circle – inherit Point class public __gc class Circle :public Point public __gc class Circle :public Point { public: public: Circle(); Circle(); Circle( int,int,double); Circle( int,int,double); __property double get_Radius(){return radius;} __property double get_Radius(){return radius;} __property void set_Radius(double r) __property void set_Radius(double r) {if( r > 0) radius = r;} {if( r > 0) radius = r;} double Diameter(); double Diameter(); double Area(); double Area(); double Circumference(); double Circumference(); String *ToString(); String *ToString(); private: private: double radius; double radius; }; };

Circle Circle::Circle(){} Circle::Circle(){} Circle::Circle(int xval,int yval, double r) :Point(xval,yval) Circle::Circle(int xval,int yval, double r) :Point(xval,yval) { radius = r;} { radius = r;} double Circle::Diameter(){ return radius *2;} double Circle::Diameter(){ return radius *2;} } double Circle::Circumference() double Circle::Circumference() { return Math::PI *Diameter(); return Math::PI *Diameter(); } double Circle::Area() double Circle::Area() { return Math::PI * Math::Pow(radius, 2);} { return Math::PI * Math::Pow(radius, 2);} String *Circle::ToString() String *Circle::ToString() { return String::Concat(S”center= “, __super::ToString(), S”;Radius = “, Radius.ToString()); { return String::Concat(S”center= “, __super::ToString(), S”;Radius = “, Radius.ToString()); }

int _tmain() int _tmain() { Circle *cir = new Circle(4,5,2.5); Circle *cir = new Circle(4,5,2.5); String *output = String::Concat(S”X coordinate is “, cir->X.ToString(), S”\nY coordinate is “, cir- >Y.ToString(), S”\nRadius is “, cir- >Radius.ToString()); String *output = String::Concat(S”X coordinate is “, cir->X.ToString(), S”\nY coordinate is “, cir- >Y.ToString(), S”\nRadius is “, cir- >Radius.ToString()); Return 0; Return 0; }

Assignment Define a class called Cylinder that inherits from Circle. Define a class called Cylinder that inherits from Circle. Has data member height Has data member height Methods: Volume() that return volume of the cylinder Methods: Volume() that return volume of the cylinder Area() return the cylinder’s surface area Area() return the cylinder’s surface area Properties: set_Height and get_Height Properties: set_Height and get_Height

int _tmain() { Cylinder *cyn = new Cylinder(12,23,2.5,5.7); String *out = String::Concat (S"X coordinate is ", cyn->X.ToString(), S"\nY coordinate is ", cyn->Y.ToString(),S"\nRadius is ", cyn->Radius.ToString(),S"\nHeight is ", cyn->Height.ToString()); out = String::Concat (out, S"\nDiameter is ", cyn->Diameter().ToString(S"F"), S"\n"); out = String::Concat (out, S"Volume is", cyn->Volume().ToString(S"F")); MessageBox::Show (out, S"Demonstrating class Cylinder"); return 0; }